246 



Prof. C. Gr. Knott on the Interactions of 



It was soon found that in good experiments the permanent 

 magnetic cycles in (1), (3), and (5) were practically identical ; 

 so that in later experiments (3) was omitted. It was also 

 established by direct experiment that the permanent magnetic 

 cycle in (2) was quite independent of the magnetic condition 

 of the wire when the linear current was put on. 



Some of the features of the case are shown in the curves 

 given. This is chosen as an average type, the departures 

 from which, when the relative magnitudes of linear current 

 and field are altered, will be briefly indicated below. In these 

 curves magnetic force (<£)) is measured horizontally, magnetic 

 intensity (30 measured vertically. The magnetic force is 



given in electromagnetic C.G.S, units ; and the magnetic 

 intensity (very roughly) in the same. 



Curve a corresponds to the permanent magnetic cycles 

 (1), (3), (5) ; curves b and c give the cycles when the linear 

 current is flowing first in the one and then in the other direc- 

 tion. The current used in this experiment was about two 

 amperes. 



A glance at these curves is sufficient to teach us that the 

 linear current modifies the properties of iron in relation to 

 the magnetic after-effect in three well marked ways. 



First, the total range of magnetic intensity produced by a 

 given cyclic variation of magnetic force is markedly dimi- 



